Inkjet printer and inkjet printing method using the same

ABSTRACT

Provided is an inkjet printer which is capable of preventing ink flow and color blurring as well as color mixing during multicolor printing when image formation is performed with aqueous ink on a web-shaped printing base material, and an inkjet printing method using the inkjet printer. The inkjet printer is configured to perform image formation by discharging aqueous ink to a web-shaped printing base material, and comprises: a conveyance mechanism configured to continuously convey the web-shaped printing base material; a single-pass system inkjet head configured to discharge, by a single-pass system, the aqueous ink to a surface of the web-shaped printing base material conveyed by the conveyance mechanism; and a surface pre-heating unit which is arranged on an upstream side of conveyance from the single-pass system inkjet head and is configured to heat at least the surface of the web-shaped printing base material, wherein image formation through use of the single-pass system inkjet head is performed on the web-shaped printing base material heated by the surface pre-heating unit.

TECHNICAL FIELD

The present invention relates to an inkjet printer which is configuredto perform single-pass system image formation with aqueous ink on aweb-shaped printing base material, and an inkjet printing method usingthe inkjet printer.

BACKGROUND ART

Hitherto, as a method of performing inkjet printing with aqueous ink ona printing base material through use of an inkjet printer, there hasbeen proposed a method of performing printing while heating the printingbase material being conveyed (Patent Document 1).

As a method of heating the printing base material being conveyed asdescribed above, there has been employed a method of heating a backsurface of the printing base material through use of a hot plate or thelike.

However, even when the back surface of the printing base material isheated through use of the hot plate or the like, there arises thefollowing problem in a case of performing printing while continuouslyconveying the printing base material. That is, when a printing speedreaches a speed of about 15 m/min, ink flow and color blurring caused byinsufficient drying of ink and the like, color mixing during multicolorprinting, and the like occur.

Further, as methods of performing printing while continuously conveyingthe printing base material, there are given a scan system and asingle-pass system. Of those systems, the single-pass system is moresuitable for high-speed printing because the single-pass system does notrequire scanning. A single-pass system inkjet recording method isdisclosed, for example, in Patent Document 2. However, when the printingspeed reaches the speed of about 15 m/min as described above, therearises a problem in that ink flow and color blurring caused byinsufficient drying of ink and the like, color mixing during multicolorprinting, and the like occur, with the result that there is difficultyin increasing the printing speed.

PRIOR ART DOCUMENTS Patent Documents Patent Document 1: JP 2014-214160 APatent Document 2: JP 2010-142966 A SUMMARY OF THE INVENTION Problems tobe solved by the Invention

It is an object of the present invention to provide an inkjet printerwhich is capable of preventing ink flow and color blurring as well ascolor mixing during multicolor printing when image formation isperformed with aqueous ink on a web-shaped printing base material, andto provide an inkjet printing method using the inkjet printer.

Means for Solving Problems

In order to solve the above-mentioned problems, an inkjet printeraccording to the present invention is an inkjet printer for aqueous inkwhich is configured to perform image formation by discharging aqueousink to a web-shaped printing base material, and comprises: a conveyancemechanism configured to continuously convey the web-shaped printing basematerial; a single-pass system inkjet head configured to discharge, by asingle-pass system, the aqueous ink to a surface of the web-shapedprinting base material conveyed by the conveyance mechanism; and asurface pre-heating unit which is arranged on an upstream side ofconveyance from the single-pass system inkjet head and is configured toheat at least the surface of the web-shaped printing base material,wherein image formation through use of the single-pass system inkjethead is performed on the web-shaped printing base material heated by thesurface pre-heating unit.

Heating by the surface pre-heating unit is preferably performed throughuse of hot air blowing means for applying hot air to the surface of theweb-shaped printing base material. As heating other than application ofhot air to the surface of the web-shaped printing base material, theweb-shaped printing base material can be heated by irradiation with alaser having a wavelength which is equal to an absorption wavelength ofthe web-shaped printing base material. Heating by irradiation withinfrared light is also conceivable. However, when the web-shapedprinting base material is a transparent film, infrared light passesthrough the web-shaped printing base material, with the result that theweb-shaped printing base material is not heated. Therefore, in the caseof heating by irradiation with infrared light, it is necessary that theweb-shaped printing base material have black color or that theweb-shaped printing base material be a base material having such awavelength as to absorb infrared light. A combination of theabove-mentioned heating through use of the hot air blowing means,heating by irradiation with a laser, and heating by irradiation withinfrared light can also be used.

For example, hot air at a temperature of from 40° C. to 80° C. ispreferably applied to the surface of the web-shaped printing basematerial through use of the hot air blowing means.

The hot air blowing means preferably comprises: a nozzle group main bodyhaving a plurality of slit-shaped hot air blowing nozzles arranged so asto form gaps therebetween, the plurality of slit-shaped hot air blowingnozzles each having a slit-shaped hot air outlet port extending in awidth direction of the web-shaped printing base material; and a suctionmechanism configured to suck an atmosphere of the gaps formed in thenozzle group main body.

The inkjet printer preferably further comprises a back surface heatingunit configured to heat a back surface of the web-shaped printing basematerial. Heating by the back surface heating unit is preferablyperformed through use of hot air blowing means or a hot plate.

Further, heating means similar to the above-mentioned surfacepre-heating unit may be arranged, as a surface post-heating unit, on adownstream side of conveyance of the web-shaped printing base materialfrom the inkjet head.

The web-shaped printing base material is preferably a transparent film.As the web-like printing base material being the transparent film, atransparent film using PET (polyethylene terephthalate), PVC (polyvinylchloride), PP (polypropylene), or the like may be suitably used.

An inkjet printing method according to the present invention comprisesperforming, through use of the said inkjet printer, single-pass systemimage formation through use of the single-pass system inkjet head withaqueous ink on the web-shaped printing base material heated by thesurface pre-heating unit of the inkjet printer.

Advantageous Effects of the Invention

According to the present invention, there is provided a remarkableeffect of being capable of providing an inkjet printer which is capableof preventing ink flow and color blurring, and color mixing duringmulticolor printing when image formation is performed with aqueous inkon a web-shaped printing base material, and an inkjet printing methodusing the inkjet printer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional structural view for illustrating one embodiment ofan inkjet printer according to the present invention.

FIG. 2 is a perspective view for illustrating an embodiment of hot airblowing means to be used in the inkjet printer of the present invention.

FIG. 3 is an enlarged view for illustrating a main portion of FIG. 1.

FIG. 4 is an enlarged view for illustrating a main portion of anotherembodiment of an inkjet printer according to the present invention.

FIG. 5 is an enlarged view for illustrating a main portion of stillanother embodiment of an inkjet printer according to the presentinvention.

MODES FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described below but thoseembodiments are described as examples and hence it is understood thatvarious modifications may be made thereto without departing from thetechnical spirit of the present invention. In addition, the same membersare denoted by the same reference symbols.

FIG. 1 is a sectional structural view for illustrating one embodiment ofan inkjet printer according to the present invention.

In FIG. 1, the reference symbol 10A denotes an inkjet printer of thepresent invention. The inkjet printer 10A is an inkjet printer foraqueous ink which is configured to perform image formation bydischarging aqueous ink to a web-shaped printing base material 12. Theinkjet printer 10A comprises: a conveyance mechanism 14 (conveyancemechanisms 14 a and 14 b in the illustrated embodiment) configured tocontinuously convey the web-shaped printing base material 12;single-pass system inkjet heads 16 a to 16 e configured to discharge, bya single-pass system, aqueous ink to a surface of the web-shapedprinting base material 12 conveyed by the conveyance mechanism 14; andsurface pre-heating units 18 a to 18 e which are arranged on an upstreamside of conveyance from the inkjet heads 16 a to 16 e and are configuredto heat at least the surface of the web-shaped printing base material12. The ink is discharged by the inkjet heads 16 a to 16 e to theweb-shaped printing base material 12 heated by the surface pre-heatingunits 18 a to 18 e. Further, surface post-heating units 18 b to 18 f arearranged on a downstream side of conveyance from the inkjet heads 16 ato 16 e so that drying of aqueous ink discharged by the inkjet heads 16a to 16 e is further accelerated.

The surface pre-heating units 18 b to 18 e also act as surfacepost-heating units and also serve as the surface post-heating units 18 bto 18 e.

As the inkjet heads 16 a to 16 e, various known single-pass systeminkjet discharge devices can be used.

As the conveyance mechanism 14, any known mechanism can also be used aslong as the mechanism can convey the web-shaped printing base material12. As illustrated in FIG. 1, it is possible to adopt a configurationcomprising drive belts 20 and 34, an original roller 22 around which theweb-shaped printing base material 12 is wound, various rollers 24, 26,28, and 30 configured to convey the web-shaped printing base material12, and a roll-up roller 32 configured to roll up the printed web-shapedprinting base material 12. There is illustrated an operator O of theinkjet printer.

Further, the original roller 22 around which the web-shaped printingbase material 12 is wound is accommodated in a heating box 36, and isheated in advance (pre-heated) to a temperature of from 60° C. to 70° C.As a method of heating in the heating box 36, heating may be performedwith hot air or by various known heaters. In the illustrated example,there is illustrated a configuration in which the inside of the heatingbox 36 is heated with hot air.

At least the surface of the web-shaped printing base material 12 heatedin advance as described above is heated by the surface pre-heating unit18 a arranged on the upstream side of conveyance from the inkjet heads16 a to 16 e. As the surface pre-heating unit 18 a, an example is givenof hot air blowing means. In the hot air blowing means, hot air at atemperature of from about 40° C. to about 80° C., for example, atemperature of 70° C. is applied to the surface of the web-shapedprinting base material 12. A time period for applying hot air is fromabout 2 seconds to about 3 seconds in the case of a printing speed of 15m/min, but is appropriately changed also depending on the temperature ofthe hot air.

An embodiment of the hot air blowing means to be used as the surfacepre-heating units 18 a to 18 e is illustrated in FIG. 2. As is wellillustrated in FIG. 2, as hot air blowing means 42 being the surfacepre-heating unit 18 a, it is possible to adopt a configurationcomprising a nozzle group main body 50 having a plurality of slit-shapedhot air blowing nozzles 46 arranged so as to form gaps 48 therebetween,the slit-shaped hot air blowing nozzles 46 each having a slit-shaped hotair outlet port 44 extending in a width direction of the web-shapedprinting base material 12, and a suction mechanism (not shown)configured to suck an atmosphere of the gaps 48 formed in the nozzlegroup main body 50. The atmosphere of the gaps 48 is sucked in adirection opposite to blowing of hot air H (direction opposite to thearrow of FIG. 2) by the suction mechanism (not shown). As the suctionmechanism, various known suction devices can be used and henceillustration thereof is omitted. Thus, the effect of reducing colorblurring and the like caused by aqueous ink is achieved through suctionof the atmosphere of the gaps 48.

Further, in the example illustrated in FIG. 1, as is well illustrated inFIG. 3, there is illustrated an example in which hot air blowing meanssimilar to the hot air blowing means serving as the surface pre-heatingunit 18 a is used also as the surface post-heating unit 18 b andarranged on the downstream side of conveyance from the inkjet head 16 a.As is well illustrated in FIG. 1 and FIG. 2, the inkjet heads 16 a to 16e are inkjet heads having respective ink storage tanks (not shown) forcyan (C), magenta (M), yellow (Y), black (B), and white (W), and aqueousink I of respective colors is discharged from the inkjet heads 16 a to16 e.

Further, in the embodiment illustrated in FIG. 1, a back surface heatingunit 38 configured to heat the web-shaped printing base material 12 froma back surface thereof is arranged. As the back surface heating unit 38,a known hot plate can be used, and for example, an electrothermal heaterhaving a filament laid on a ceramic plate can be used. When the hotplate is used as the back surface heating unit 38, it is suitable thatthe hot plate be used after being heated to a temperature of, forexample, from 40° C. to 65° C. It is appropriate that the back surfaceheating unit 38 be arranged so as to correspond to the inkjet heads 16 ato 16 e. The back surface heating unit 38 may also be arranged acrosssetting positions of the inkjet heads 16 a to 16 e as illustrated inFIG. 1, or can also be arranged in accordance with each setting positionof the inkjet heads 16 a to 16 e.

Further, as the back surface heating unit 38, the hot air blowing meanssimilar to the surface pre-heating unit 18 a can also be used. Further,when the hot air blowing means is used as the back surface heating unit38, it is suitable that, for example, hot air at a temperature of from40° C. to 80° C. be applied to the back surface of the web-shapedprinting base material 12.

In FIG. 4, there is illustrated an example in which the hot air blowingmeans is used as the back surface heating unit 38. In FIG. 4, there isillustrated hot air blowing means 52 serving as the back surface heatingunit 38. The configuration other than arrangement of the hot air blowingmeans 52 as the back surface heating unit 38 is the same as theabove-mentioned configuration.

Next, still another embodiment of an inkjet printer according to thepresent invention is illustrated in FIG. 5.

In FIG. 5, the reference symbol 10B denotes another embodiment of aninkjet printer of the present invention. In the inkjet printer 10B, asadditional surface post-heating units, laser irradiation devices 40 a to40 e are arranged on the downstream side of conveyance from the inkjetheads 16 a to 16 e. The configuration of the inkjet printer 10B is thesame as that of the inkjet printer 10A described above except that thelaser irradiation devices 40 a to 40 e are arranged.

With the inkjet printers 10A and 10B constructed as described above,when ink discharge by the inkjet heads 16 a to 16 e is performed withaqueous ink to the web-shaped printing base material 12 heated by thesurface pre-heating unit 18 a of the inkjet printers 10A and 10B,printing can be suitably performed with respect to a transparent PETfilm as the web-shaped printing base material without ink flow and colorblurring, color mixing during multicolor printing, and the like even ata printing speed of 15 m/min. Further, as illustrated in the inkjetprinters 10A and 10B, when the surface post-heating units and the backsurface heating unit are combined, ink flow and ink blurring, colormixing during multicolor printing, and the like are further eliminated,and printing can be suitably performed.

REFERENCE SIGNS LIST

10A, 10B: inkjet printer, 12: web-shaped printing base material, 14, 14a, 14 b: conveyance mechanism, 16 a to 16 e: single-pass system inkjethead, 18 a to 18 e: surface pre-heating unit, 18 b to 18 f: surfacepost-heating unit, 20, 34: drive belt, 22: original roller, 24, 26, 28,30: roller, 32: roll-up roller, 36: heating box, 38: back surfaceheating unit, 40 a to 40 e: laser irradiation device, 42, 52: hot airblowing means, 44: slit-shaped hot air outlet port, 46: slit-shaped hotair blowing nozzle, 48: gap, 50: nozzle group main body, H: hot air, I:aqueous ink, O: operator.

In the claims:
 1. An inkjet printer for aqueous ink which is configured to perform image formation by discharging aqueous ink to a web-shaped printing base material, the inkjet printer comprising: a conveyance mechanism configured to continuously convey the web-shaped printing base material; a single-pass system inkjet head configured to discharge, by a single-pass system, the aqueous ink to a surface of the web-shaped printing base material conveyed by the conveyance mechanism; and a surface pre-heating unit arranged on an upstream side of conveyance from the single-pass system inkjet head and the surface pre-heating unit being configured to heat at least the surface of the web-shaped printing base material, wherein image formation through use of the single-pass system inkjet head is performed on the web-shaped printing base material heated by the surface pre-heating unit.
 2. An inkjet printer according to claim 1, wherein heating by the surface pre-heating unit is performed via a hot air blowing means for applying hot air to the surface of the web-shaped printing base material.
 3. An inkjet printer according to claim 2, wherein the hot air blowing means comprises: a nozzle group main body having a plurality of slit-shaped hot air blowing nozzles arranged to form gaps therebetween, each of the plurality of slit-shaped hot air blowing nozzles having a slit-shaped hot air outlet port extending in a width direction of the web-shaped printing base material; and a suction mechanism configured to suck an atmosphere of the gaps formed in the nozzle group main body.
 4. An inkjet printer according to claim 1, further comprising a back surface heating unit configured to heat a back surface of the web-shaped printing base material.
 5. An inkjet printer according to claim 4, wherein heating by the back surface heating unit is performed via one of a hot air blowing means and a hot plate.
 6. An inkjet printer according to 1, wherein the web-shaped printing base material is a transparent film.
 7. An inkjet printing method, comprising: providing an inkjet printer comprising: a conveyance mechanism configured to continuously convey a web-shaped printing base material; a single-pass system inkjet head configured to discharge, by a single-pass system, the aqueous ink to a surface of the web-shaped printing base material conveyed by the conveyance mechanism; and a surface pre-heating unit arranged on an upstream side of conveyance from the single-pass system inkjet head and the surface pre-heating unit is configured to heat at least the surface of the web-shaped printing base material; performing, via the inkjet printer, single-pass system image formation via the single-pass system inkjet head with aqueous ink on the web-shaped printing base material heated by the surface pre-heating unit of the inkjet printer.
 8. An inkjet printing method according to claim 7, wherein heating by the surface pre-heating unit is performed via a hot air blowing means for applying hot air to the surface of the web-shaped printing base material.
 9. An inkjet printing method according to claim 8, wherein the hot air blowing means comprises: a nozzle group main body having a plurality of slit-shaped hot air blowing nozzles arranged to form gaps therebetween, each of the plurality of slit-shaped hot air blowing nozzles having a slit-shaped hot air outlet port extending in a width direction of the web-shaped printing base material; and a suction mechanism configured to suck an atmosphere of the gaps formed in the nozzle group main body.
 10. An inkjet printing method according to claim 7, further comprising: providing a back surface heating unit configured to heat a back surface of the web-shaped printing base material.
 11. An inkjet printing method according to claim 10, wherein heating by the back surface heating unit is performed via one of a hot air blowing means and a hot plate.
 12. An inkjet printing method according to claim 7, wherein the web-shaped printing base material is a transparent film. 